Management of Light in Illumination. 115 



remarks as may be necessary, in order to illustrate the 

 principles on which they have been constructed. 



When new inventions are recommended to the pub- 

 lic, calculated to produce a total change in habits long 

 established, no hope can reasonably be entertained of 

 their being adopted, unless pains be taken to show 

 their utility in the plainest and most convincing 

 manner. 



I shall first give an account of the means that have 

 been used for suspending the pendulous illuminators ; 

 and, as there is nothing either new or complicated in 

 this machinery, it may be described in a few words. 



A strong hoop of brass, of about i inch in width, is 

 suspended from the ceiling of the room in a position 

 perfectly horizontal, by means of six chains attached to 

 six arrows of brass, of about 0.4 of an inch in diameter 

 and 6.9 inches in length, which project horizontally 

 from the outside of the hoop, to which they are firmly 

 fixed. These chains, which are each about 30 inches 

 in length, are all fixed above to the bottom of an orna- 

 mented baldaquin, which is a hoop of brass in the form 

 of a crown, of about 9 inches in diameter ; which hoop 

 is suspended in a horizontal position by means of a 

 double cord, which passes over two pulleys fixed in a 

 small block, which is attached by means of a hook to 

 a staple fixed in the ceiling. This cord descends and 

 is attached to a counterpoise of lead in the form of 

 a large tassel, ornamented by gilding. This tassel 

 being made hollow, the cord by which the illuminator 

 is suspended passing through it, is kept in its place. 



The length of the cord is such that, when the illu-- 

 minator is at a proper height, the heavy tassel, which 

 serves as a counterpoise to it, has descended so low as- 



